Immunogenicity of the ChAdOx1 nCoV-19 and the BBV152 Vaccines in Patients with Autoimmune Rheumatic Diseases

Introduction: There is limited information on the effectiveness of COVID-19 vaccination in patients with autoimmune rheumatic diseases (AIRD). Methods: 136 consecutive patients with rheumatic diseases who never had a diagnosis of COVID-19 previously, and had completed vaccination with either the ChAdOx1 or BBV152 vaccines were recruited. Their IgG antibody titres to the Spike protein were estimated 1 month after the second dose. Results: 102 patients had AIRD while the 34 had non-AIRD. Lesser patients with AIRD (92/102) had positive antibodies titres than ones with non-AIRD(33/34) [p<0.001]. Amongst patients who received the ChAdOX1 vaccine, the AIRD group had lower antibody titres. Although the AIRD patients receiving BBV152 had similarly lower titres numerically, this did not attain statistical significance probably due to lesser numbers. Comparing the two vaccines, 114(95%) of those who received ChAdOx1 (n=120) and 11(68.7%) of those who received BBV152(n=16) had detectable antibodies [p=0.004] . Antibody titres also were higher in ChAdOx1 recipients when compared to BBV152. To validate the findings, we estimated antibody titres in 30 healthy people each who had received either vaccine. All 30 who had received ChAdOX1 and only 23/30 of those who had received BBV152 had positive antibodies (p=0.011). Conclusion: In this preliminary analysis, patients with AIRD had lower seroconversion rates as well as lower antibody titres as compared to patients with non-AIRD. Also,the humoral immunogenicity of the BBV152 vaccine appears to be less than that of the ChAdOX1 vaccine. Validation using larger numbers and testing of cellular immunity is urgently required.